I've been meaning to lighten that rule. Critique is appreciative but not exactly necessary as some posts can be based solely on comments, but the comments should have a reason. If they're posting "nice x sprite, it's awesome," then I don't exactly allow it but if they added onto it more and gave reason such as defining the clean outline or clean shading, design, concept, etc. then it would be a good comment.

Constructive criticism is an important part of an art forum, it helps the artist better himself/herself. Although I said it is appreciative, it's also highly recommended because I'm sure the artists themselves want to improve.The rule for the showcase thread says that there must be constructive criticism because it's not any ordinary gallery thread with multiple kinds of sprites and pixel art. The main point to the showcase thread is to point out one piece out of the others and have it improved by receiving CC.